Interior trim automobile components commonly have cushioned, soft-touch aesthetic features. In particular, automotive interior door panels often have localized cushioned areas in tile armrest or bolster area. Such localized softness may be imparted by a flexible-foam or elastomeric pad of varying thickness surrounded by a relatively harder durometer cover sheet material.
A number of processes have been proposed for making cushioned armrests and the like in automotive interior door panels. U.S. Pat. No. 5,073,318 for a "Vehicle Inner Panel" discloses a first forming step of molding a substrate layer followed by a second step of molding a foam padding material between the substrate layer and an elastomeric facing layer. U.S. Pat. No. 5,224,299 for "Vehicular Door Structure" describes a door trim including a foamed pad member, an outer skin member for covering the foamed pad member, and a framework embedded in the foamed pad member for reinforcing the door trim. U.S. Pat. No. 4,474,635 for "Method of Selective Bonding of Textile Materials" teaches a method for compressing the molten surface of a non-woven substrate layer into the interstices of a surface fabric after first positioning a piece of foam cushioning therebetween.
Reaction injection molding is a known process for forming molded articles between male and female mold halves; see BASF U.S. Pat. No. 5,208,269. A known interior panel incorporating a cushioned armrest made by reaction injection molding includes a foam pad sandwiched between a vinyl cover and a polyurethane panel substrate. The foam is compressed due to the pressure of molding, e.g., up to about 55 psi, then expands once as the pressure is released. Since the molded back or substrate of the door panel is rigid, the foam presses outwardly against the cover, forming an unsightly visible bulge in the area of the armrest tracing the outline of the armrest cushion.
According to another version of such a product, this outline, or "read line" was eliminated by thickening the cover material so that bulging did not occur. However, such thickening made the armrest stiffer and, to a large extent, defeated the purpose of having a cushion in the first place. When touching this armrest, the user can barely feel that a cushion is present, and the feel of the armrest is essentially rigid like the cover material. Thus, a need persists for a cushioned armrest construction that can be made using injection molding that provides a soft., cushioned feel, yet avoids unsightly bulging caused by rebounding of the cushion.